X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/a907dc69fb71e3559601cbe87832b9a1c9f5250e..3570640e437ae864e53616c1c9bff5f57d91030b:/man/mule.texi diff --git a/man/mule.texi b/man/mule.texi index 88f52d6e21..9369fcaca2 100644 --- a/man/mule.texi +++ b/man/mule.texi @@ -1,5 +1,6 @@ @c This is part of the Emacs manual. -@c Copyright (C) 1997, 1999, 2000, 2001 Free Software Foundation, Inc. +@c Copyright (C) 1997, 1999, 2000, 2001, 2002, 2003, 2004, +@c 2005, 2006, 2007 Free Software Foundation, Inc. @c See file emacs.texi for copying conditions. @node International, Major Modes, Frames, Top @chapter International Character Set Support @@ -35,13 +36,11 @@ @cindex Dutch @cindex Spanish Emacs supports a wide variety of international character sets, -including European variants of the Latin alphabet, as well as Chinese, -Cyrillic, Devanagari (Hindi and Marathi), Ethiopic, Greek, Hebrew, IPA, -Japanese, Korean, Lao, Thai, Tibetan, and Vietnamese scripts. These features -have been merged from the modified version of Emacs known as MULE (for -``MULti-lingual Enhancement to GNU Emacs'') - - Emacs also supports various encodings of these characters used by +including European and Vietnamese variants of the Latin alphabet, as +well as Cyrillic, Devanagari (for Hindi and Marathi), Ethiopic, Greek, +Han (for Chinese and Japanese), Hangul (for Korean), Hebrew, IPA, +Kannada, Lao, Malayalam, Tamil, Thai, Tibetan, and Vietnamese scripts. +Emacs also supports various encodings of these characters used by other internationalized software, such as word processors and mailers. Emacs allows editing text with international characters by supporting @@ -49,33 +48,35 @@ all the related activities: @itemize @bullet @item -You can visit files with non-ASCII characters, save non-ASCII text, and -pass non-ASCII text between Emacs and programs it invokes (such as +You can visit files with non-@acronym{ASCII} characters, save non-@acronym{ASCII} text, and +pass non-@acronym{ASCII} text between Emacs and programs it invokes (such as compilers, spell-checkers, and mailers). Setting your language environment (@pxref{Language Environments}) takes care of setting up the coding systems and other options for a specific language or culture. Alternatively, you can specify how Emacs should encode or decode text -for each command; see @ref{Specify Coding}. +for each command; see @ref{Text Coding}. @item -You can display non-ASCII characters encoded by the various scripts. -This works by using appropriate fonts on X and similar graphics -displays (@pxref{Defining Fontsets}), and by sending special codes to -text-only displays (@pxref{Specify Coding}). If some characters are -displayed incorrectly, refer to @ref{Undisplayable Characters}, which -describes possible problems and explains how to solve them. +You can display non-@acronym{ASCII} characters encoded by the various +scripts. This works by using appropriate fonts on graphics displays +(@pxref{Defining Fontsets}), and by sending special codes to text-only +displays (@pxref{Terminal Coding}). If some characters are displayed +incorrectly, refer to @ref{Undisplayable Characters}, which describes +possible problems and explains how to solve them. @item -You can insert non-ASCII characters or search for them. To do that, +You can insert non-@acronym{ASCII} characters or search for them. To do that, you can specify an input method (@pxref{Select Input Method}) suitable for your language, or use the default input method set up when you set -your language environment. (Emacs input methods are part of the Leim -package, which must be installed for you to be able to use them.) If -your keyboard can produce non-ASCII characters, you can select an -appropriate keyboard coding system (@pxref{Specify Coding}), and Emacs +your language environment. If +your keyboard can produce non-@acronym{ASCII} characters, you can select an +appropriate keyboard coding system (@pxref{Terminal Coding}), and Emacs will accept those characters. Latin-1 characters can also be input by -using the @kbd{C-x 8} prefix, see @ref{Single-Byte Character Support, -C-x 8}. +using the @kbd{C-x 8} prefix, see @ref{Unibyte Mode}. + +On X Window systems, your locale should be set to an appropriate value +to make sure Emacs interprets keyboard input correctly; see +@ref{Language Environments, locales}. @end itemize The rest of this chapter describes these issues in detail. @@ -90,28 +91,35 @@ C-x 8}. * Coding Systems:: Character set conversion when you read and write files, and so on. * Recognize Coding:: How Emacs figures out which conversion to use. -* Specify Coding:: Various ways to choose which conversion to use. +* Specify Coding:: Specifying a file's coding system explicitly. +* Output Coding:: Choosing coding systems for output. +* Text Coding:: Choosing conversion to use for file text. +* Communication Coding:: Coding systems for interprocess communication. +* File Name Coding:: Coding systems for file @emph{names}. +* Terminal Coding:: Specifying coding systems for converting + terminal input and output. * Fontsets:: Fontsets are collections of fonts that cover the whole spectrum of characters. * Defining Fontsets:: Defining a new fontset. * Undisplayable Characters:: When characters don't display. -* Single-Byte Character Support:: - You can pick one European character set - to use without multibyte characters. +* Unibyte Mode:: You can pick one European character set + to use without multibyte characters. +* Charsets:: How Emacs groups its internal character codes. @end menu @node International Chars @section Introduction to International Character Sets - The users of international character sets and scripts have established -many more-or-less standard coding systems for storing files. Emacs -internally uses a single multibyte character encoding, so that it can -intermix characters from all these scripts in a single buffer or string. -This encoding represents each non-ASCII character as a sequence of bytes -in the range 0200 through 0377. Emacs translates between the multibyte -character encoding and various other coding systems when reading and -writing files, when exchanging data with subprocesses, and (in some -cases) in the @kbd{C-q} command (@pxref{Multibyte Conversion}). + The users of international character sets and scripts have +established many more-or-less standard coding systems for storing +files. Emacs internally uses a single multibyte character encoding, +so that it can intermix characters from all these scripts in a single +buffer or string. This encoding represents each non-@acronym{ASCII} +character as a sequence of bytes in the range 0200 through 0377. +Emacs translates between the multibyte character encoding and various +other coding systems when reading and writing files, when exchanging +data with subprocesses, and (in some cases) in the @kbd{C-q} command +(@pxref{Multibyte Conversion}). @kindex C-h h @findex view-hello-file @@ -132,48 +140,27 @@ language, to make it convenient to type them. The prefix key @kbd{C-x @key{RET}} is used for commands that pertain to multibyte characters, coding systems, and input methods. -@ignore -@c This is commented out because it doesn't fit here, or anywhere. -@c This manual does not discuss "character sets" as they -@c are used in Mule, and it makes no sense to mention these commands -@c except as part of a larger discussion of the topic. -@c But it is not clear that topic is worth mentioning here, -@c since that is more of an implementation concept -@c than a user-level concept. And when we switch to Unicode, -@c character sets in the current sense may not even exist. - -@findex list-charset-chars -@cindex characters in a certain charset - The command @kbd{M-x list-charset-chars} prompts for a name of a -character set, and displays all the characters in that character set. - -@findex describe-character-set -@cindex character set, description - The command @kbd{M-x describe-character-set} prompts for a character -set name and displays information about that character set, including -its internal representation within Emacs. -@end ignore - @node Enabling Multibyte @section Enabling Multibyte Characters -@cindex turn multibyte support on or off - You can enable or disable multibyte character support, either for -Emacs as a whole, or for a single buffer. When multibyte characters are -disabled in a buffer, then each byte in that buffer represents a -character, even codes 0200 through 0377. The old features for -supporting the European character sets, ISO Latin-1 and ISO Latin-2, -work as they did in Emacs 19 and also work for the other ISO 8859 -character sets. - - However, there is no need to turn off multibyte character support to -use ISO Latin; the Emacs multibyte character set includes all the -characters in these character sets, and Emacs can translate -automatically to and from the ISO codes. - By default, Emacs starts in multibyte mode, because that allows you to use all the supported languages and scripts without limitations. +@cindex turn multibyte support on or off + You can enable or disable multibyte character support, either for +Emacs as a whole, or for a single buffer. When multibyte characters +are disabled in a buffer, we call that @dfn{unibyte mode}. Then each +byte in that buffer represents a character, even codes 0200 through +0377. + + The old features for supporting the European character sets, ISO +Latin-1 and ISO Latin-2, work in unibyte mode as they did in Emacs 19 +and also work for the other ISO 8859 character sets. However, there +is no need to turn off multibyte character support to use ISO Latin; +the Emacs multibyte character set includes all the characters in these +character sets, and Emacs can translate automatically to and from the +ISO codes. + To edit a particular file in unibyte representation, visit it using @code{find-file-literally}. @xref{Visiting}. To convert a buffer in multibyte representation into a single-byte representation of the same @@ -181,7 +168,7 @@ characters, the easiest way is to save the contents in a file, kill the buffer, and find the file again with @code{find-file-literally}. You can also use @kbd{C-x @key{RET} c} (@code{universal-coding-system-argument}) and specify @samp{raw-text} as -the coding system with which to find or save a file. @xref{Specify +the coding system with which to find or save a file. @xref{Text Coding}. Finding a file as @samp{raw-text} doesn't disable format conversion, uncompression and auto mode selection as @code{find-file-literally} does. @@ -206,30 +193,32 @@ in that buffer. @cindex Lisp files, and multibyte operation @cindex multibyte operation, and Lisp files @cindex unibyte operation, and Lisp files -@cindex init file, and non-ASCII characters -@cindex environment variables, and non-ASCII characters +@cindex init file, and non-@acronym{ASCII} characters +@cindex environment variables, and non-@acronym{ASCII} characters With @samp{--unibyte}, multibyte strings are not created during initialization from the values of environment variables, -@file{/etc/passwd} entries etc.@: that contain non-ASCII 8-bit +@file{/etc/passwd} entries etc.@: that contain non-@acronym{ASCII} 8-bit characters. Emacs normally loads Lisp files as multibyte, regardless of whether -you used @samp{--unibyte}. This includes the Emacs initialization -file, @file{.emacs}, and the initialization files of Emacs packages -such as Gnus. However, you can specify unibyte loading for a -particular Lisp file, by putting @w{@samp{-*-unibyte: t;-*-}} in a -comment on the first line. Then that file is always loaded as unibyte -text, even if you did not start Emacs with @samp{--unibyte}. The -motivation for these conventions is that it is more reliable to always -load any particular Lisp file in the same way. However, you can load -a Lisp file as unibyte, on any one occasion, by typing @kbd{C-x +you used @samp{--unibyte}. This includes the Emacs initialization file, +@file{.emacs}, and the initialization files of Emacs packages such as +Gnus. However, you can specify unibyte loading for a particular Lisp +file, by putting @w{@samp{-*-unibyte: t;-*-}} in a comment on the first +line (@pxref{File Variables}). Then that file is always loaded as +unibyte text, even if you did not start Emacs with @samp{--unibyte}. +The motivation for these conventions is that it is more reliable to +always load any particular Lisp file in the same way. However, you can +load a Lisp file as unibyte, on any one occasion, by typing @kbd{C-x @key{RET} c raw-text @key{RET}} immediately before loading it. - The mode line indicates whether multibyte character support is enabled -in the current buffer. If it is, there are two or more characters (most -often two dashes) before the colon near the beginning of the mode line. -When multibyte characters are not enabled, just one dash precedes the -colon. + The mode line indicates whether multibyte character support is +enabled in the current buffer. If it is, there are two or more +characters (most often two dashes) near the beginning of the mode +line, before the indication of the visited file's end-of-line +convention (colon, backslash, etc.). When multibyte characters +are not enabled, nothing precedes the colon except a single dash. +@xref{Mode Line}, for more details about this. @node Language Environments @section Language Environments @@ -251,20 +240,28 @@ Each language environment also specifies a default input method. @findex set-language-environment @vindex current-language-environment - To select a language environment, customize the option + To select a language environment, you can customize the variable @code{current-language-environment} or use the command @kbd{M-x set-language-environment}. It makes no difference which buffer is current when you use this command, because the effects apply globally to the Emacs session. The supported language environments include: @cindex Euro sign +@cindex UTF-8 @quotation -Chinese-BIG5, Chinese-CNS, Chinese-GB, Cyrillic-ALT, Cyrillic-ISO, -Cyrillic-KOI8, Czech, Devanagari, Dutch, English, Ethiopic, German, -Greek, Hebrew, IPA, Japanese, Korean, Lao, Latin-1, Latin-2, Latin-3, -Latin-4, Latin-5, Latin-8 (Celtic), Latin-9 (updated Latin-1, with the -Euro sign), Polish, Romanian, Slovak, Slovenian, Spanish, Thai, -Tibetan, Turkish, and Vietnamese. +Belarusian, Brazilian Portuguese, Bulgarian, Chinese-BIG5, +Chinese-CNS, Chinese-EUC-TW, Chinese-GB, Croatian, Cyrillic-ALT, +Cyrillic-ISO, Cyrillic-KOI8, Czech, Devanagari, Dutch, English, +Ethiopic, French, Georgian, German, Greek, Hebrew, IPA, Italian, +Japanese, Kannada, Korean, Lao, Latin-1, Latin-2, Latin-3, +Latin-4, Latin-5, Latin-6, Latin-7, Latin-8 (Celtic), +Latin-9 (updated Latin-1 with the Euro sign), Latvian, +Lithuanian, Malayalam, Polish, Romanian, Russian, Slovak, +Slovenian, Spanish, Swedish, Tajik, Tamil, Thai, Tibetan, +Turkish, UTF-8 (for a setup which prefers Unicode characters and +files encoded in UTF-8), Ukrainian, Vietnamese, Welsh, and +Windows-1255 (for a setup which prefers Cyrillic characters and +files encoded in Windows-1255). @end quotation @cindex fonts for various scripts @@ -272,7 +269,7 @@ Tibetan, Turkish, and Vietnamese. To display the script(s) used by your language environment on a graphical display, you need to have a suitable font. If some of the characters appear as empty boxes, you should install the GNU Intlfonts -package, which includes fonts for all supported scripts.@footnote{If +package, which includes fonts for most supported scripts.@footnote{If you run Emacs on X, you need to inform the X server about the location of the newly installed fonts with the following commands: @@ -297,8 +294,9 @@ against entries in the value of the variables @code{locale-charset-language-names} and @code{locale-language-names}, and selects the corresponding language environment if a match is found. (The former variable overrides the latter.) It also adjusts the display -table and terminal coding system, the locale coding system, and the -preferred coding system as needed for the locale. +table and terminal coding system, the locale coding system, the +preferred coding system as needed for the locale, and---last but not +least---the way Emacs decodes non-@acronym{ASCII} characters sent by your keyboard. If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG} environment variables while running Emacs, you may want to invoke the @@ -324,12 +322,12 @@ file. @findex describe-language-environment To display information about the effects of a certain language environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env} -@key{RET}} (@code{describe-language-environment}). This tells you which -languages this language environment is useful for, and lists the +@key{RET}} (@code{describe-language-environment}). This tells you +which languages this language environment is useful for, and lists the character sets, coding systems, and input methods that go with it. It -also shows some sample text to illustrate scripts used in this language -environment. By default, this command describes the chosen language -environment. +also shows some sample text to illustrate scripts used in this +language environment. If you give an empty input for @var{lang-env}, +this command describes the chosen language environment. @vindex set-language-environment-hook You can customize any language environment with the normal hook @@ -362,14 +360,14 @@ has its own input method; sometimes several languages which use the same characters can share one input method. A few languages support several input methods. - The simplest kind of input method works by mapping ASCII letters + The simplest kind of input method works by mapping @acronym{ASCII} letters into another alphabet; this allows you to use one other alphabet -instead of ASCII. The Greek and Russian input methods +instead of @acronym{ASCII}. The Greek and Russian input methods work this way. A more powerful technique is composition: converting sequences of characters into one letter. Many European input methods use composition -to produce a single non-ASCII letter from a sequence that consists of a +to produce a single non-@acronym{ASCII} letter from a sequence that consists of a letter followed by accent characters (or vice versa). For example, some methods convert the sequence @kbd{a'} into a single accented letter. These input methods have no special commands of their own; all they do @@ -435,15 +433,18 @@ immediately delete it. For example, you could type @kbd{e e @key{DEL} Another method, more general but not quite as easy to type, is to use @kbd{C-\ C-\} between two characters to stop them from combining. This is the command @kbd{C-\} (@code{toggle-input-method}) used twice. -@ifinfo +@ifnottex @xref{Select Input Method}. -@end ifinfo +@end ifnottex @cindex incremental search, input method interference @kbd{C-\ C-\} is especially useful inside an incremental search, because it stops waiting for more characters to combine, and starts searching for what you have already entered. + To find out how to input the character after point using the current +input method, type @kbd{C-u C-x =}. @xref{Position Info}. + @vindex input-method-verbose-flag @vindex input-method-highlight-flag The variables @code{input-method-highlight-flag} and @@ -455,12 +456,6 @@ most input methods---some disable this feature). If possible characters to type next is displayed in the echo area (but not when you are in the minibuffer). -@cindex Leim package - Input methods are implemented in the separate Leim package: they are -available only if the system administrator used Leim when building -Emacs. If Emacs was built without Leim, you will find that no input -methods are defined. - @node Select Input Method @section Selecting an Input Method @@ -493,12 +488,12 @@ Display a list of all the supported input methods. input method name from the minibuffer; the name normally starts with the language environment that it is meant to be used with. The variable @code{current-input-method} records which input method is selected. - + @findex toggle-input-method @kindex C-\ - Input methods use various sequences of ASCII characters to stand for -non-ASCII characters. Sometimes it is useful to turn off the input -method temporarily. To do this, type @kbd{C-\} + Input methods use various sequences of @acronym{ASCII} characters to +stand for non-@acronym{ASCII} characters. Sometimes it is useful to +turn off the input method temporarily. To do this, type @kbd{C-\} (@code{toggle-input-method}). To reenable the input method, type @kbd{C-\} again. @@ -544,17 +539,24 @@ for those scripts. How to do this remapping properly depends on your actual keyboard layout. To specify which layout your keyboard has, use the command @kbd{M-x quail-set-keyboard-layout}. +@findex quail-show-key + You can use the command @kbd{M-x quail-show-key} to show what key (or +key sequence) to type in order to input the character following point, +using the selected keyboard layout. The command @kbd{C-u C-x =} also +shows that information in addition to the other information about the +character. + @findex list-input-methods - To display a list of all the supported input methods, type @kbd{M-x + To see a list of all the supported input methods, type @kbd{M-x list-input-methods}. The list gives information about each input method, including the string that stands for it in the mode line. @node Multibyte Conversion -@section Unibyte and Multibyte Non-ASCII characters +@section Unibyte and Multibyte Non-@acronym{ASCII} characters When multibyte characters are enabled, character codes 0240 (octal) through 0377 (octal) are not really legitimate in the buffer. The valid -non-ASCII printing characters have codes that start from 0400. +non-@acronym{ASCII} printing characters have codes that start from 0400. If you type a self-inserting character in the range 0240 through 0377, or if you use @kbd{C-q} to insert one, Emacs assumes you @@ -565,9 +567,9 @@ through your choice of language environment @iftex (see above). @end iftex -@ifinfo +@ifnottex (@pxref{Language Environments}). -@end ifinfo +@end ifnottex If you do not specify a choice, the default is Latin-1. If you insert a character in the range 0200 through 0237, which @@ -599,14 +601,23 @@ coding systems @code{no-conversion}, @code{raw-text} and @cindex international files from DOS/Windows systems A special class of coding systems, collectively known as @dfn{codepages}, is designed to support text encoded by MS-Windows and -MS-DOS software. To use any of these systems, you need to create it -with @kbd{M-x codepage-setup}. @xref{MS-DOS and MULE}. After -creating the coding system for the codepage, you can use it as any -other coding system. For example, to visit a file encoded in codepage -850, type @kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename} -@key{RET}}. - - In addition to converting various representations of non-ASCII +MS-DOS software. The names of these coding systems are +@code{cp@var{nnnn}}, where @var{nnnn} is a 3- or 4-digit number of the +codepage. You can use these encodings just like any other coding +system; for example, to visit a file encoded in codepage 850, type +@kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename} +@key{RET}}@footnote{ +In the MS-DOS port of Emacs, you need to create a @code{cp@var{nnn}} +coding system with @kbd{M-x codepage-setup}, before you can use it. +@iftex +@xref{MS-DOS and MULE,,,emacs-extra,Specialized Emacs Features}. +@end iftex +@ifnottex +@xref{MS-DOS and MULE}. +@end ifnottex +}. + + In addition to converting various representations of non-@acronym{ASCII} characters, a coding system can perform end-of-line conversion. Emacs handles three different conventions for how to separate lines in a file: newline, carriage-return linefeed, and just carriage-return. @@ -625,7 +636,8 @@ Display a list of all the supported coding systems. @kindex C-h C @findex describe-coding-system The command @kbd{C-h C} (@code{describe-coding-system}) displays -information about particular coding systems. You can specify a coding +information about particular coding systems, including the end-of-line +conversion specified by those coding systems. You can specify a coding system name as the argument; alternatively, with an empty argument, it describes the coding systems currently selected for various purposes, both in the current buffer and as the defaults, and the priority list @@ -638,6 +650,7 @@ system, including the letter that stands for it in the mode line (@pxref{Mode Line}). @cindex end-of-line conversion +@cindex line endings @cindex MS-DOS end-of-line conversion @cindex Macintosh end-of-line conversion Each of the coding systems that appear in this list---except for @@ -676,17 +689,25 @@ predictable. For example, the coding system @code{iso-latin-1} has variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and @code{iso-latin-1-mac}. +@cindex @code{undecided}, coding system + The coding systems @code{unix}, @code{dos}, and @code{mac} are +aliases for @code{undecided-unix}, @code{undecided-dos}, and +@code{undecided-mac}, respectively. These coding systems specify only +the end-of-line conversion, and leave the character code conversion to +be deduced from the text itself. + The coding system @code{raw-text} is good for a file which is mainly -ASCII text, but may contain byte values above 127 which are not meant to -encode non-ASCII characters. With @code{raw-text}, Emacs copies those -byte values unchanged, and sets @code{enable-multibyte-characters} to -@code{nil} in the current buffer so that they will be interpreted -properly. @code{raw-text} handles end-of-line conversion in the usual -way, based on the data encountered, and has the usual three variants to -specify the kind of end-of-line conversion to use. +@acronym{ASCII} text, but may contain byte values above 127 which are +not meant to encode non-@acronym{ASCII} characters. With +@code{raw-text}, Emacs copies those byte values unchanged, and sets +@code{enable-multibyte-characters} to @code{nil} in the current buffer +so that they will be interpreted properly. @code{raw-text} handles +end-of-line conversion in the usual way, based on the data +encountered, and has the usual three variants to specify the kind of +end-of-line conversion to use. In contrast, the coding system @code{no-conversion} specifies no -character code conversion at all---none for non-ASCII byte values and +character code conversion at all---none for non-@acronym{ASCII} byte values and none for end of line. This is useful for reading or writing binary files, tar files, and other files that must be examined verbatim. It, too, sets @code{enable-multibyte-characters} to @code{nil}. @@ -697,10 +718,28 @@ the @kbd{M-x find-file-literally} command. This uses might convert the file contents before you see them. @xref{Visiting}. The coding system @code{emacs-mule} means that the file contains -non-ASCII characters stored with the internal Emacs encoding. It +non-@acronym{ASCII} characters stored with the internal Emacs encoding. It handles end-of-line conversion based on the data encountered, and has the usual three variants to specify the kind of end-of-line conversion. +@findex unify-8859-on-decoding-mode +@anchor{Character Translation} + The @dfn{character translation} feature can modify the effect of +various coding systems, by changing the internal Emacs codes that +decoding produces. For instance, the command +@code{unify-8859-on-decoding-mode} enables a mode that ``unifies'' the +Latin alphabets when decoding text. This works by converting all +non-@acronym{ASCII} Latin-@var{n} characters to either Latin-1 or +Unicode characters. This way it is easier to use various +Latin-@var{n} alphabets together. (In a future Emacs version we hope +to move towards full Unicode support and complete unification of +character sets.) + +@vindex enable-character-translation + If you set the variable @code{enable-character-translation} to +@code{nil}, that disables all character translation (including +@code{unify-8859-on-decoding-mode}). + @node Recognize Coding @section Recognizing Coding Systems @@ -730,12 +769,12 @@ Czech, you probably want Latin-2 to be preferred. This is one of the reasons to specify a language environment. @findex prefer-coding-system - However, you can alter the priority list in detail with the command -@kbd{M-x prefer-coding-system}. This command reads the name of a coding -system from the minibuffer, and adds it to the front of the priority -list, so that it is preferred to all others. If you use this command -several times, each use adds one element to the front of the priority -list. + However, you can alter the coding system priority list in detail +with the command @kbd{M-x prefer-coding-system}. This command reads +the name of a coding system from the minibuffer, and adds it to the +front of the priority list, so that it is preferred to all others. If +you use this command several times, each use adds one element to the +front of the priority list. If you use a coding system that specifies the end-of-line conversion type, such as @code{iso-8859-1-dos}, what this means is that Emacs @@ -748,10 +787,10 @@ file. The variable @code{file-coding-system-alist} specifies this correspondence. There is a special function @code{modify-coding-system-alist} for adding elements to this list. For example, to read and write all @samp{.txt} files using the coding system -@code{china-iso-8bit}, you can execute this Lisp expression: +@code{chinese-iso-8bit}, you can execute this Lisp expression: @smallexample -(modify-coding-system-alist 'file "\\.txt\\'" 'china-iso-8bit) +(modify-coding-system-alist 'file "\\.txt\\'" 'chinese-iso-8bit) @end smallexample @noindent @@ -790,62 +829,90 @@ the buffer. The default value of @code{inhibit-iso-escape-detection} is @code{nil}. We recommend that you not change it permanently, only for one specific operation. That's because many Emacs Lisp source files -in the Emacs distribution contain non-ASCII characters encoded in the +in the Emacs distribution contain non-@acronym{ASCII} characters encoded in the coding system @code{iso-2022-7bit}, and they won't be decoded correctly when you visit those files if you suppress the escape sequence detection. -@vindex coding - You can specify the coding system for a particular file using the -@w{@samp{-*-@dots{}-*-}} construct at the beginning of a file, or a -local variables list at the end (@pxref{File Variables}). You do this -by defining a value for the ``variable'' named @code{coding}. Emacs -does not really have a variable @code{coding}; instead of setting a -variable, this uses the specified coding system for the file. For -example, @samp{-*-mode: C; coding: latin-1;-*-} specifies use of the -Latin-1 coding system, as well as C mode. When you specify the coding -explicitly in the file, that overrides -@code{file-coding-system-alist}. - @vindex auto-coding-alist @vindex auto-coding-regexp-alist - The variables @code{auto-coding-alist} and -@code{auto-coding-regexp-alist} are the strongest way to specify the -coding system for certain patterns of file names, or for files -containing certain patterns; these variables even override -@samp{-*-coding:-*-} tags in the file itself. Emacs uses -@code{auto-coding-alist} for tar and archive files, to prevent it +@vindex auto-coding-functions + The variables @code{auto-coding-alist}, +@code{auto-coding-regexp-alist} and @code{auto-coding-functions} are +the strongest way to specify the coding system for certain patterns of +file names, or for files containing certain patterns; these variables +even override @samp{-*-coding:-*-} tags in the file itself. Emacs +uses @code{auto-coding-alist} for tar and archive files, to prevent it from being confused by a @samp{-*-coding:-*-} tag in a member of the archive and thinking it applies to the archive file as a whole. Likewise, Emacs uses @code{auto-coding-regexp-alist} to ensure that -RMAIL files, whose names in general don't match any particular pattern, -are decoded correctly. +RMAIL files, whose names in general don't match any particular +pattern, are decoded correctly. One of the builtin +@code{auto-coding-functions} detects the encoding for XML files. + +@vindex rmail-decode-mime-charset + When you get new mail in Rmail, each message is translated +automatically from the coding system it is written in, as if it were a +separate file. This uses the priority list of coding systems that you +have specified. If a MIME message specifies a character set, Rmail +obeys that specification, unless @code{rmail-decode-mime-charset} is +@code{nil}. + +@vindex rmail-file-coding-system + For reading and saving Rmail files themselves, Emacs uses the coding +system specified by the variable @code{rmail-file-coding-system}. The +default value is @code{nil}, which means that Rmail files are not +translated (they are read and written in the Emacs internal character +code). + +@node Specify Coding +@section Specifying a File's Coding System If Emacs recognizes the encoding of a file incorrectly, you can reread the file using the correct coding system by typing @kbd{C-x -@key{RET} c @var{coding-system} @key{RET} M-x revert-buffer -@key{RET}}. To see what coding system Emacs actually used to decode -the file, look at the coding system mnemonic letter near the left edge -of the mode line (@pxref{Mode Line}), or type @kbd{C-h C @key{RET}}. +@key{RET} r @var{coding-system} @key{RET}}. To see what coding system +Emacs actually used to decode the file, look at the coding system +mnemonic letter near the left edge of the mode line (@pxref{Mode +Line}), or type @kbd{C-h C @key{RET}}. + +@vindex coding + You can specify the coding system for a particular file in the file +itself, using the @w{@samp{-*-@dots{}-*-}} construct at the beginning, +or a local variables list at the end (@pxref{File Variables}). You do +this by defining a value for the ``variable'' named @code{coding}. +Emacs does not really have a variable @code{coding}; instead of +setting a variable, this uses the specified coding system for the +file. For example, @samp{-*-mode: C; coding: latin-1;-*-} specifies +use of the Latin-1 coding system, as well as C mode. When you specify +the coding explicitly in the file, that overrides +@code{file-coding-system-alist}. + + If you add the character @samp{!} at the end of the coding system +name in @code{coding}, it disables any character translation +(@pxref{Character Translation}) while decoding the file. This is +useful when you need to make sure that the character codes in the +Emacs buffer will not vary due to changes in user settings; for +instance, for the sake of strings in Emacs Lisp source files. + +@node Output Coding +@section Choosing Coding Systems for Output @vindex buffer-file-coding-system Once Emacs has chosen a coding system for a buffer, it stores that -coding system in @code{buffer-file-coding-system} and uses that coding -system, by default, for operations that write from this buffer into a -file. This includes the commands @code{save-buffer} and -@code{write-region}. If you want to write files from this buffer using -a different coding system, you can specify a different coding system for -the buffer using @code{set-buffer-file-coding-system} (@pxref{Specify -Coding}). - - You can insert any possible character into any Emacs buffer, but -most coding systems can only handle some of the possible characters. -This means that it is possible for you to insert characters that -cannot be encoded with the coding system that will be used to save the -buffer. For example, you could start with an ASCII file and insert a -few Latin-1 characters into it, or you could edit a text file in -Polish encoded in @code{iso-8859-2} and add some Russian words to it. -When you save the buffer, Emacs cannot use the current value of +coding system in @code{buffer-file-coding-system}. That makes it the +default for operations that write from this buffer into a file, such +as @code{save-buffer} and @code{write-region}. You can specify a +different coding system for further file output from the buffer using +@code{set-buffer-file-coding-system} (@pxref{Text Coding}). + + You can insert any character Emacs supports into any Emacs buffer, +but most coding systems can only handle a subset of these characters. +Therefore, you can insert characters that cannot be encoded with the +coding system that will be used to save the buffer. For example, you +could start with an @acronym{ASCII} file and insert a few Latin-1 +characters into it, or you could edit a text file in Polish encoded in +@code{iso-8859-2} and add some Russian words to it. When you save +that buffer, Emacs cannot use the current value of @code{buffer-file-coding-system}, because the characters you added cannot be encoded by that coding system. @@ -860,12 +927,12 @@ contents, and asks you to choose one of those coding systems. If you insert the unsuitable characters in a mail message, Emacs behaves a bit differently. It additionally checks whether the most-preferred coding system is recommended for use in MIME messages; -if not, Emacs tells you that the most-preferred coding system is -not recommended and prompts you for another coding system. This is so -you won't inadvertently send a message encoded in a way that your -recipient's mail software will have difficulty decoding. (If you do -want to use the most-preferred coding system, you can still type its -name in response to the question.) +if not, Emacs tells you that the most-preferred coding system is not +recommended and prompts you for another coding system. This is so you +won't inadvertently send a message encoded in a way that your +recipient's mail software will have difficulty decoding. (You can +still use an unsuitable coding system if you type its name in response +to the question.) @vindex sendmail-coding-system When you send a message with Mail mode (@pxref{Sending Mail}), Emacs has @@ -878,63 +945,47 @@ new files, which is controlled by your choice of language environment, if that is non-@code{nil}. If all of these three values are @code{nil}, Emacs encodes outgoing mail using the Latin-1 coding system. -@vindex rmail-decode-mime-charset - When you get new mail in Rmail, each message is translated -automatically from the coding system it is written in, as if it were a -separate file. This uses the priority list of coding systems that you -have specified. If a MIME message specifies a character set, Rmail -obeys that specification, unless @code{rmail-decode-mime-charset} is -@code{nil}. - -@vindex rmail-file-coding-system - For reading and saving Rmail files themselves, Emacs uses the coding -system specified by the variable @code{rmail-file-coding-system}. The -default value is @code{nil}, which means that Rmail files are not -translated (they are read and written in the Emacs internal character -code). - -@node Specify Coding -@section Specifying a Coding System +@node Text Coding +@section Specifying a Coding System for File Text In cases where Emacs does not automatically choose the right coding -system, you can use these commands to specify one: +system for a file's contents, you can use these commands to specify +one: @table @kbd @item C-x @key{RET} f @var{coding} @key{RET} -Use coding system @var{coding} for the visited file -in the current buffer. +Use coding system @var{coding} for saving or revisiting the visited +file in the current buffer. @item C-x @key{RET} c @var{coding} @key{RET} Specify coding system @var{coding} for the immediately following command. -@item C-x @key{RET} k @var{coding} @key{RET} -Use coding system @var{coding} for keyboard input. - -@item C-x @key{RET} t @var{coding} @key{RET} -Use coding system @var{coding} for terminal output. +@item C-x @key{RET} r @var{coding} @key{RET} +Revisit the current file using the coding system @var{coding}. -@item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET} -Use coding systems @var{input-coding} and @var{output-coding} for -subprocess input and output in the current buffer. - -@item C-x @key{RET} x @var{coding} @key{RET} -Use coding system @var{coding} for transferring selections to and from -other programs through the window system. - -@item C-x @key{RET} X @var{coding} @key{RET} -Use coding system @var{coding} for transferring @emph{one} -selection---the next one---to or from the window system. +@item M-x recode-region @key{RET} @var{right} @key{RET} @var{wrong} @key{RET} +Convert a region that was decoded using coding system @var{wrong}, +decoding it using coding system @var{right} instead. @end table @kindex C-x RET f @findex set-buffer-file-coding-system - The command @kbd{C-x @key{RET} f} (@code{set-buffer-file-coding-system}) -specifies the file coding system for the current buffer---in other -words, which coding system to use when saving or rereading the visited -file. You specify which coding system using the minibuffer. Since this -command applies to a file you have already visited, it affects only the -way the file is saved. + The command @kbd{C-x @key{RET} f} +(@code{set-buffer-file-coding-system}) sets the file coding system for +the current buffer---in other words, it says which coding system to +use when saving or reverting the visited file. You specify which +coding system using the minibuffer. If you specify a coding system +that cannot handle all of the characters in the buffer, Emacs warns +you about the troublesome characters when you actually save the +buffer. + +@cindex specify end-of-line conversion + You can also use this command to specify the end-of-line conversion +(@pxref{Coding Systems, end-of-line conversion}) for encoding the +current buffer. For example, @kbd{C-x @key{RET} f dos @key{RET}} will +cause Emacs to save the current buffer's text with DOS-style CRLF line +endings. @kindex C-x RET c @findex universal-coding-system-argument @@ -947,17 +998,18 @@ command}. So if the immediately following command is @kbd{C-x C-f}, for example, it reads the file using that coding system (and records the coding -system for when the file is saved). Or if the immediately following +system for when you later save the file). Or if the immediately following command is @kbd{C-x C-w}, it writes the file using that coding system. -Other file commands affected by a specified coding system include -@kbd{C-x C-i} and @kbd{C-x C-v}, as well as the other-window variants of -@kbd{C-x C-f}. - - @kbd{C-x @key{RET} c} also affects commands that start subprocesses, -including @kbd{M-x shell} (@pxref{Shell}). +When you specify the coding system for saving in this way, instead +of with @kbd{C-x @key{RET} f}, there is no warning if the buffer +contains characters that the coding system cannot handle. - However, if the immediately following command does not use the coding -system, then @kbd{C-x @key{RET} c} ultimately has no effect. + Other file commands affected by a specified coding system include +@kbd{C-x i} and @kbd{C-x C-v}, as well as the other-window variants +of @kbd{C-x C-f}. @kbd{C-x @key{RET} c} also affects commands that +start subprocesses, including @kbd{M-x shell} (@pxref{Shell}). If the +immediately following command does not use the coding system, then +@kbd{C-x @key{RET} c} ultimately has no effect. An easy way to visit a file with no conversion is with the @kbd{M-x find-file-literally} command. @xref{Visiting}. @@ -970,50 +1022,51 @@ in a file. Selecting a language environment typically sets this variable to a good choice of default coding system for that language environment. -@kindex C-x RET t -@findex set-terminal-coding-system - The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system}) -specifies the coding system for terminal output. If you specify a -character code for terminal output, all characters output to the -terminal are translated into that coding system. +@kindex C-x RET r +@findex revert-buffer-with-coding-system + If you visit a file with a wrong coding system, you can correct this +with @kbd{C-x @key{RET} r} (@code{revert-buffer-with-coding-system}). +This visits the current file again, using a coding system you specify. - This feature is useful for certain character-only terminals built to -support specific languages or character sets---for example, European -terminals that support one of the ISO Latin character sets. You need to -specify the terminal coding system when using multibyte text, so that -Emacs knows which characters the terminal can actually handle. +@findex recode-region + If a piece of text has already been inserted into a buffer using the +wrong coding system, you can redo the decoding of it using @kbd{M-x +recode-region}. This prompts you for the proper coding system, then +for the wrong coding system that was actually used, and does the +conversion. It first encodes the region using the wrong coding system, +then decodes it again using the proper coding system. - By default, output to the terminal is not translated at all, unless -Emacs can deduce the proper coding system from your terminal type or -your locale specification (@pxref{Language Environments}). +@node Communication Coding +@section Coding Systems for Interprocess Communication -@kindex C-x RET k -@findex set-keyboard-coding-system -@vindex keyboard-coding-system - The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system}) -or the Custom option @code{keyboard-coding-system} -specifies the coding system for keyboard input. Character-code -translation of keyboard input is useful for terminals with keys that -send non-ASCII graphic characters---for example, some terminals designed -for ISO Latin-1 or subsets of it. + This section explains how to specify coding systems for use +in communication with other processes. - By default, keyboard input is not translated at all. +@table @kbd +@item C-x @key{RET} x @var{coding} @key{RET} +Use coding system @var{coding} for transferring selections to and from +other window-based applications. - There is a similarity between using a coding system translation for -keyboard input, and using an input method: both define sequences of -keyboard input that translate into single characters. However, input -methods are designed to be convenient for interactive use by humans, and -the sequences that are translated are typically sequences of ASCII -printing characters. Coding systems typically translate sequences of -non-graphic characters. +@item C-x @key{RET} X @var{coding} @key{RET} +Use coding system @var{coding} for transferring @emph{one} +selection---the next one---to or from another window-based application. + +@item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET} +Use coding systems @var{input-coding} and @var{output-coding} for +subprocess input and output in the current buffer. + +@item C-x @key{RET} c @var{coding} @key{RET} +Specify coding system @var{coding} for the immediately following +command. +@end table @kindex C-x RET x @kindex C-x RET X @findex set-selection-coding-system @findex set-next-selection-coding-system The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system}) -specifies the coding system for sending selected text to the window -system, and for receiving the text of selections made in other +specifies the coding system for sending selected text to other windowing +applications, and for receiving the text of selections made in other applications. This command applies to all subsequent selections, until you override it by using the command again. The command @kbd{C-x @key{RET} X} (@code{set-next-selection-coding-system}) specifies the @@ -1028,23 +1081,56 @@ own buffer, and thus you can use this command to specify translation to and from a particular subprocess by giving the command in the corresponding buffer. + You can also use @kbd{C-x @key{RET} c} just before the command that +runs or starts a subprocess, to specify the coding system to use for +communication with that subprocess. + The default for translation of process input and output depends on the current language environment. +@vindex locale-coding-system +@cindex decoding non-@acronym{ASCII} keyboard input on X + The variable @code{locale-coding-system} specifies a coding system +to use when encoding and decoding system strings such as system error +messages and @code{format-time-string} formats and time stamps. That +coding system is also used for decoding non-@acronym{ASCII} keyboard input on X +Window systems. You should choose a coding system that is compatible +with the underlying system's text representation, which is normally +specified by one of the environment variables @env{LC_ALL}, +@env{LC_CTYPE}, and @env{LANG}. (The first one, in the order +specified above, whose value is nonempty is the one that determines +the text representation.) + +@node File Name Coding +@section Coding Systems for File Names + +@table @kbd +@item C-x @key{RET} F @var{coding} @key{RET} +Use coding system @var{coding} for encoding and decoding file +@emph{names}. +@end table + @vindex file-name-coding-system -@cindex file names with non-ASCII characters - The variable @code{file-name-coding-system} specifies a coding system -to use for encoding file names. If you set the variable to a coding -system name (as a Lisp symbol or a string), Emacs encodes file names -using that coding system for all file operations. This makes it -possible to use non-ASCII characters in file names---or, at least, those -non-ASCII characters which the specified coding system can encode. - - If @code{file-name-coding-system} is @code{nil}, Emacs uses a default -coding system determined by the selected language environment. In the -default language environment, any non-ASCII characters in file names are -not encoded specially; they appear in the file system using the internal -Emacs representation. +@cindex file names with non-@acronym{ASCII} characters + The variable @code{file-name-coding-system} specifies a coding +system to use for encoding file names. It has no effect on reading +and writing the @emph{contents} of files. + +@findex set-file-name-coding-system +@kindex C-x @key{RET} F + If you set the variable to a coding system name (as a Lisp symbol or +a string), Emacs encodes file names using that coding system for all +file operations. This makes it possible to use non-@acronym{ASCII} +characters in file names---or, at least, those non-@acronym{ASCII} +characters which the specified coding system can encode. Use @kbd{C-x +@key{RET} F} (@code{set-file-name-coding-system}) to specify this +interactively. + + If @code{file-name-coding-system} is @code{nil}, Emacs uses a +default coding system determined by the selected language environment. +In the default language environment, any non-@acronym{ASCII} +characters in file names are not encoded specially; they appear in the +file system using the internal Emacs representation. @strong{Warning:} if you change @code{file-name-coding-system} (or the language environment) in the middle of an Emacs session, problems can @@ -1055,48 +1141,109 @@ these buffers under the visited file name, saving may use the wrong file name, or it may get an error. If such a problem happens, use @kbd{C-x C-w} to specify a new file name for that buffer. -@vindex locale-coding-system - The variable @code{locale-coding-system} specifies a coding system -to use when encoding and decoding system strings such as system error -messages and @code{format-time-string} formats and time stamps. You -should choose a coding system that is compatible with the underlying -system's text representation, which is normally specified by one of -the environment variables @env{LC_ALL}, @env{LC_CTYPE}, and -@env{LANG}. (The first one, in the order specified above, whose value -is nonempty is the one that determines the text representation.) +@findex recode-file-name + If a mistake occurs when encoding a file name, use the command +@kbd{M-x recode-file-name} to change the file name's coding +system. This prompts for an existing file name, its old coding +system, and the coding system to which you wish to convert. + +@node Terminal Coding +@section Coding Systems for Terminal I/O + +@table @kbd +@item C-x @key{RET} k @var{coding} @key{RET} +Use coding system @var{coding} for keyboard input. + +@item C-x @key{RET} t @var{coding} @key{RET} +Use coding system @var{coding} for terminal output. +@end table + +@kindex C-x RET t +@findex set-terminal-coding-system + The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system}) +specifies the coding system for terminal output. If you specify a +character code for terminal output, all characters output to the +terminal are translated into that coding system. + + This feature is useful for certain character-only terminals built to +support specific languages or character sets---for example, European +terminals that support one of the ISO Latin character sets. You need to +specify the terminal coding system when using multibyte text, so that +Emacs knows which characters the terminal can actually handle. + + By default, output to the terminal is not translated at all, unless +Emacs can deduce the proper coding system from your terminal type or +your locale specification (@pxref{Language Environments}). + +@kindex C-x RET k +@findex set-keyboard-coding-system +@vindex keyboard-coding-system + The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system}) +or the variable @code{keyboard-coding-system} specifies the coding +system for keyboard input. Character-code translation of keyboard +input is useful for terminals with keys that send non-@acronym{ASCII} +graphic characters---for example, some terminals designed for ISO +Latin-1 or subsets of it. + + By default, keyboard input is translated based on your system locale +setting. If your terminal does not really support the encoding +implied by your locale (for example, if you find it inserts a +non-@acronym{ASCII} character if you type @kbd{M-i}), you will need to set +@code{keyboard-coding-system} to @code{nil} to turn off encoding. +You can do this by putting + +@lisp +(set-keyboard-coding-system nil) +@end lisp + +@noindent +in your @file{~/.emacs} file. + + There is a similarity between using a coding system translation for +keyboard input, and using an input method: both define sequences of +keyboard input that translate into single characters. However, input +methods are designed to be convenient for interactive use by humans, and +the sequences that are translated are typically sequences of @acronym{ASCII} +printing characters. Coding systems typically translate sequences of +non-graphic characters. @node Fontsets @section Fontsets @cindex fontsets - A font for X typically defines shapes for a single alphabet or script. + A font typically defines shapes for a single alphabet or script. Therefore, displaying the entire range of scripts that Emacs supports requires a collection of many fonts. In Emacs, such a collection is called a @dfn{fontset}. A fontset is defined by a list of fonts, each assigned to handle a range of character codes. - Each fontset has a name, like a font. The available X fonts are -defined by the X server; fontsets, however, are defined within Emacs -itself. Once you have defined a fontset, you can use it within Emacs by -specifying its name, anywhere that you could use a single font. Of -course, Emacs fontsets can use only the fonts that the X server -supports; if certain characters appear on the screen as hollow boxes, -this means that the fontset in use for them has no font for those -characters.@footnote{The Emacs installation instructions have information on -additional font support.} + Each fontset has a name, like a font. However, while fonts are +stored in the system and the available font names are defined by the +system, fontsets are defined within Emacs itself. Once you have +defined a fontset, you can use it within Emacs by specifying its name, +anywhere that you could use a single font. Of course, Emacs fontsets +can use only the fonts that the system supports; if certain characters +appear on the screen as hollow boxes, this means that the fontset in +use for them has no font for those characters.@footnote{The Emacs +installation instructions have information on additional font +support.} Emacs creates two fontsets automatically: the @dfn{standard fontset} and the @dfn{startup fontset}. The standard fontset is most likely to -have fonts for a wide variety of non-ASCII characters; however, this is -not the default for Emacs to use. (By default, Emacs tries to find a -font that has bold and italic variants.) You can specify use of the -standard fontset with the @samp{-fn} option, or with the @samp{Font} X -resource (@pxref{Font X}). For example, +have fonts for a wide variety of non-@acronym{ASCII} characters; +however, this is not the default for Emacs to use. (By default, Emacs +tries to find a font that has bold and italic variants.) You can +specify use of the standard fontset with the @samp{-fn} option. For +example, @example emacs -fn fontset-standard @end example +@noindent +You can also specify a fontset with the @samp{Font} resource (@pxref{X +Resources}). + A fontset does not necessarily specify a font for every character code. If a fontset specifies no font for a certain character, or if it specifies a font that does not exist on your system, then it cannot @@ -1123,7 +1270,7 @@ created automatically. Their names have @samp{bold} instead of @samp{medium}, or @samp{i} instead of @samp{r}, or both. @cindex startup fontset - If you specify a default ASCII font with the @samp{Font} resource or + If you specify a default @acronym{ASCII} font with the @samp{Font} resource or the @samp{-fn} argument, Emacs generates a fontset from it automatically. This is the @dfn{startup fontset} and its name is @code{fontset-startup}. It does this by replacing the @var{foundry}, @@ -1157,7 +1304,7 @@ menus cannot handle fontsets. The resource value should have this form: @smallexample -@var{fontpattern}, @r{[}@var{charsetname}:@var{fontname}@r{]@dots{}} +@var{fontpattern}, @r{[}@var{charset}:@var{font}@r{]@dots{}} @end smallexample @noindent @@ -1177,7 +1324,7 @@ number of times in defining one fontset. For the other character sets, Emacs chooses a font based on @var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values -that describe the character set. For the ASCII character font, +that describe the character set. For the @acronym{ASCII} character font, @samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}. In addition, when several consecutive fields are wildcards, Emacs @@ -1194,7 +1341,7 @@ does. @end example @noindent -the font specification for ASCII characters would be this: +the font specification for @acronym{ASCII} characters would be this: @example -*-fixed-medium-r-normal-*-24-*-ISO8859-1 @@ -1233,31 +1380,31 @@ call this function explicitly to create a fontset. @node Undisplayable Characters @section Undisplayable Characters - Your terminal may be unable to display some non-ASCII -characters. Most non-windowing terminals can only use a single -character set (use the variable @code{default-terminal-coding-system} -(@pxref{Specify Coding}) to tell Emacs which one); characters which + There may be a some non-@acronym{ASCII} characters that your terminal cannot +display. Most text-only terminals support just a single character +set (use the variable @code{default-terminal-coding-system} +(@pxref{Terminal Coding}) to tell Emacs which one); characters which can't be encoded in that coding system are displayed as @samp{?} by default. - Windowing terminals can display a broader range of characters, but + Graphical displays can display a broader range of characters, but you may not have fonts installed for all of them; characters that have no font appear as a hollow box. If you use Latin-1 characters but your terminal can't display -Latin-1, you can arrange to display mnemonic ASCII sequences +Latin-1, you can arrange to display mnemonic @acronym{ASCII} sequences instead, e.g.@: @samp{"o} for o-umlaut. Load the library @file{iso-ascii} to do this. @vindex latin1-display If your terminal can display Latin-1, you can display characters from other European character sets using a mixture of equivalent -Latin-1 characters and ASCII mnemonics. Use the Custom option -@code{latin1-display} to enable this. The mnemonic ASCII +Latin-1 characters and @acronym{ASCII} mnemonics. Customize the variable +@code{latin1-display} to enable this. The mnemonic @acronym{ASCII} sequences mostly correspond to those of the prefix input methods. -@node Single-Byte Character Support -@section Single-byte Character Set Support +@node Unibyte Mode +@section Unibyte Editing Mode @cindex European character sets @cindex accented characters @@ -1274,13 +1421,13 @@ such as @samp{Latin-@var{n}}. For more information about unibyte operation, see @ref{Enabling Multibyte}. Note particularly that you probably want to ensure that -your initialization files are read as unibyte if they contain non-ASCII -characters. +your initialization files are read as unibyte if they contain +non-@acronym{ASCII} characters. @vindex unibyte-display-via-language-environment Emacs can also display those characters, provided the terminal or font -in use supports them. This works automatically. Alternatively, if you -are using a window system, Emacs can also display single-byte characters +in use supports them. This works automatically. Alternatively, on a +graphical display, Emacs can also display single-byte characters through fontsets, in effect by displaying the equivalent multibyte characters according to the current language environment. To request this, set the variable @code{unibyte-display-via-language-environment} @@ -1288,7 +1435,7 @@ to a non-@code{nil} value. @cindex @code{iso-ascii} library If your terminal does not support display of the Latin-1 character -set, Emacs can display these characters as ASCII sequences which at +set, Emacs can display these characters as @acronym{ASCII} sequences which at least give you a clear idea of what the characters are. To do this, load the library @code{iso-ascii}. Similar libraries for other Latin-@var{n} character sets could be implemented, but we don't have @@ -1301,60 +1448,86 @@ inclusive) are displayed as octal escapes. You can change this for non-standard ``extended'' versions of ISO-8859 character sets by using the function @code{standard-display-8bit} in the @code{disp-table} library. - There are several ways you can input single-byte non-ASCII + There are two ways to input single-byte non-@acronym{ASCII} characters: @itemize @bullet @cindex 8-bit input +@item +You can use an input method for the selected language environment. +@xref{Input Methods}. When you use an input method in a unibyte buffer, +the non-@acronym{ASCII} character you specify with it is converted to unibyte. + @item If your keyboard can generate character codes 128 (decimal) and up, -representing non-ASCII characters, you can type those character codes +representing non-@acronym{ASCII} characters, you can type those character codes directly. -On a windowing terminal, you should not need to do anything special to -use these keys; they should simply work. On a text-only terminal, you +On a graphical display, you should not need to do anything special to use +these keys; they should simply work. On a text-only terminal, you should use the command @code{M-x set-keyboard-coding-system} or the -Custom option @code{keyboard-coding-system} to specify which coding -system your keyboard uses (@pxref{Specify Coding}). Enabling this -feature will probably require you to use @kbd{ESC} to type Meta -characters; however, on a Linux console or in @code{xterm}, you can -arrange for Meta to be converted to @kbd{ESC} and still be able type -8-bit characters present directly on the keyboard or using -@kbd{Compose} or @kbd{AltGr} keys. @xref{User Input}. - -@item -You can use an input method for the selected language environment. -@xref{Input Methods}. When you use an input method in a unibyte buffer, -the non-ASCII character you specify with it is converted to unibyte. +variable @code{keyboard-coding-system} to specify which coding system +your keyboard uses (@pxref{Terminal Coding}). Enabling this feature +will probably require you to use @kbd{ESC} to type Meta characters; +however, on a console terminal or in @code{xterm}, you can arrange for +Meta to be converted to @kbd{ESC} and still be able type 8-bit +characters present directly on the keyboard or using @kbd{Compose} or +@kbd{AltGr} keys. @xref{User Input}. @kindex C-x 8 @cindex @code{iso-transl} library @cindex compose character @cindex dead character @item -For Latin-1 only, you can use the -key @kbd{C-x 8} as a ``compose character'' prefix for entry of -non-ASCII Latin-1 printing characters. @kbd{C-x 8} is good for -insertion (in the minibuffer as well as other buffers), for searching, -and in any other context where a key sequence is allowed. +For Latin-1 only, you can use the key @kbd{C-x 8} as a ``compose +character'' prefix for entry of non-@acronym{ASCII} Latin-1 printing +characters. @kbd{C-x 8} is good for insertion (in the minibuffer as +well as other buffers), for searching, and in any other context where +a key sequence is allowed. @kbd{C-x 8} works by loading the @code{iso-transl} library. Once that -library is loaded, the @key{ALT} modifier key, if you have one, serves -the same purpose as @kbd{C-x 8}; use @key{ALT} together with an accent -character to modify the following letter. In addition, if you have keys -for the Latin-1 ``dead accent characters,'' they too are defined to -compose with the following character, once @code{iso-transl} is loaded. -Use @kbd{C-x 8 C-h} to list the available translations as mnemonic -command names. - -@item -@cindex @code{iso-acc} library -@cindex ISO Accents mode -@findex iso-accents-mode -@cindex Latin-1, Latin-2 and Latin-3 input mode -For Latin-1, Latin-2 and Latin-3, @kbd{M-x iso-accents-mode} enables -a minor mode that works much like the @code{latin-1-prefix} input -method, but does not depend on having the input methods installed. This -mode is buffer-local. It can be customized for various languages with -@kbd{M-x iso-accents-customize}. +library is loaded, the @key{ALT} modifier key, if the keyboard has +one, serves the same purpose as @kbd{C-x 8}: use @key{ALT} together +with an accent character to modify the following letter. In addition, +if the keyboard has keys for the Latin-1 ``dead accent characters,'' +they too are defined to compose with the following character, once +@code{iso-transl} is loaded. + +Use @kbd{C-x 8 C-h} to list all the available @kbd{C-x 8} translations. @end itemize + +@node Charsets +@section Charsets +@cindex charsets + + Emacs groups all supported characters into disjoint @dfn{charsets}. +Each character code belongs to one and only one charset. For +historical reasons, Emacs typically divides an 8-bit character code +for an extended version of @acronym{ASCII} into two charsets: +@acronym{ASCII}, which covers the codes 0 through 127, plus another +charset which covers the ``right-hand part'' (the codes 128 and up). +For instance, the characters of Latin-1 include the Emacs charset +@code{ascii} plus the Emacs charset @code{latin-iso8859-1}. + + Emacs characters belonging to different charsets may look the same, +but they are still different characters. For example, the letter +@samp{o} with acute accent in charset @code{latin-iso8859-1}, used for +Latin-1, is different from the letter @samp{o} with acute accent in +charset @code{latin-iso8859-2}, used for Latin-2. + +@findex list-charset-chars +@cindex characters in a certain charset +@findex describe-character-set + There are two commands for obtaining information about Emacs +charsets. The command @kbd{M-x list-charset-chars} prompts for a name +of a character set, and displays all the characters in that character +set. The command @kbd{M-x describe-character-set} prompts for a +charset name and displays information about that charset, including +its internal representation within Emacs. + + To find out which charset a character in the buffer belongs to, +put point before it and type @kbd{C-u C-x =}. + +@ignore + arch-tag: 310ba60d-31ef-4ce7-91f1-f282dd57b6b3 +@end ignore